There is a small chance that the poster is really a concerned physician who really enjoys posting to Anti-QAnon subreddits during their free time, but looking at the user’s posting history, I highly doubt it.

• Began posting around March, posts often, and almost exclusively about the vaccine.
• Claims to be a doctor/physician in a very large number of posts.
• Gives out medical advice over the internet.
• Gets wrong basic details, such as claiming that an mRNA vaccine contains proteins.
• It is quite a coincidence that such a dramatic event occured to someone who spends such a large amount of time writing on reddit about the anti-vax.

I think that this is a character that someone made up.

The deleted comments from this account also show that in the past the user would “speak with doctors” instead of claiming to be one.

https://camas.github.io/reddit-search/#{"author":"thanosrain","resultSize":100}